Drug & supplement interaction

Stinging Nettle + Warfarin

Warfarin brand name: Warfarin.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Stinging Nettle has a moderate interaction with Warfarin. There is some concern that stinging nettle might decrease the effects of anticoagulant drugs such as warfarin.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Stinging Nettle and Warfarin

Here is the interaction we found between these two, with the evidence behind it.

Moderate

WARFARIN (Coumadin)

There is some concern that stinging nettle might decrease the effects of anticoagulant drugs such as warfarin.
Stinging nettle contains a significant amount of vitamin K. When taken in large quantities, this might interfere with the activity of warfarin.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing with warfarin: it works by blocking how your body uses vitamin K to make clotting factors. Stinging nettle naturally contains a fair bit of vitamin K, so loading up on it could give your body more of the very thing warfarin is trying to keep in check. In plain terms, large or concentrated amounts of nettle might weaken warfarin's blood-thinning effect, which could let your INR drop and raise your clot risk.

I want to be honest: this concern is mostly theoretical, based on how nettle and warfarin work, not strong human studies. Small amounts probably won't rock the boat much. But because warfarin is so finicky, even small swings matter. Please check with your pharmacist or doctor before adding a nettle supplement, and don't change your dose on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Stinging Nettle Also Interacts With Other Medications

Stinging Nettle has 163 moderate known drug interactions in our database — the Warfarin one above is one of them. If you take anything else, check it against the full list below.

Moderate 163 No known interaction 2,667 (incl. Warfarin)
Taking anything else?

Check Another of Your Medications Against Stinging Nettle

Covers the 2,830 medications we’ve checked against Stinging Nettle. Pick one to open its full report.

From our Q&A

Questions About Stinging Nettle or Warfarin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Stinging Nettle or Warfarin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Warfarin

This page covers Stinging Nettle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin page lists 361 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (major), American Ginseng (major), Beer (major) and Cannabis (major).

By severity: 16 major · 301 moderate · 44 minor.

From our pharmacist’s overview on the Warfarin page

“People take warfarin to prevent dangerous clots, and many are the same people reaching for glucosamine for sore joints or a multivitamin containing vitamin K, which makes this a list that deserves genuine respect. Of the 361 supplements on file for warfarin, 16 carry a major rating, and the danger runs in both directions: some add to w…”

Reviewed by 2 · Jul 18, 2026

Open the Warfarin interaction page

One more smart check

Taking Stinging Nettle as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,276 real supplement products containing Stinging Nettle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Stinging Nettle. Your product may carry other ingredients that interact with Warfarin too, on top of Stinging Nettle — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Stinging Nettle and Warfarin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Stinging Nettle
Top 10%

#80 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Warfarin
Top 10

#4 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Stinging Nettle

What is Stinging Nettle?

Stinging Nettle
  • Enlarged prostate (BPH) symptoms
  • Seasonal allergies
  • Joint pain and arthritis
  • Urinary symptoms / mild diuretic
  • Blood sugar support

Stinging nettle is a common plant used as food and in traditional medicine, most often for prostate symptoms, allergies, and joint pain. The evidence is mixed and mostly preliminary, so it is best thought of as a supportive option rather than a proven treatment. It is generally well tolerated, but pregnant and breastfeeding people should avoid it and everyone should check with a pharmacist or doctor first.

Read the full Stinging Nettle monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand name: Warfarin

Warfarin sodium tablets and Jantoven tablets are both used to prevent and treat venous thrombosis (blood clots in the veins) and pulmonary embolism (a clot in the lungs). They are also used to prevent clot-related complications in people with atrial fibrillation (an irregular heart rhythm) or who have had a heart valve replaced.

In people who have had a heart attack, warfarin is used to reduce the risk of death, another heart attack, stroke, or other clotting events. It does not dissolve an existing clot, but it helps prevent the clot from growing and stops new dangerous clots from forming.

See full Warfarin drug information
Keep checking

Other Drugs & Stinging Nettle

Browse every other medication we’ve checked against Stinging Nettle — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
163Moderate
0Minor
2,666No known interaction
163 Moderate 2,666 No interaction
Moderate

163 interactions

Showing 60 of 163 moderate interactions — see all 163 on the Stinging Nettle page.

No interaction 2,666 drugs checked — show the list

We also checked Stinging Nettle against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,666 medications checked with no known interaction — see the full Stinging Nettle list.

See the full Stinging Nettle interactions page
See every supplement checked against Warfarin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Stinging Nettle monograph › Uses, safety, and every drug interaction in one place Warfarin supplement interactions › Every supplement checked against Warfarin, ranked by severity Warfarin drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Stinging Nettle and Warfarin Together: Common Questions

Can you take Stinging Nettle with Warfarin?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Stinging Nettle and Warfarin interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Warfarin and Stinging Nettle?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.